util.c

[alex medvedev <alexm () pycckue org>]

hallo,

shouldn't prefix_len be initialized to 32 instead of 33?
otherwise first bitmask[prefix_len] in the while loop
becomes bitmask[33], which corresponds
to the 34th element of a 33 element array.

see below.

-alexm
-------------

in util.c:


/*
 * Convert a 32-bit netmask to prefixlen if possible
 * the function returns the prefix-len; if plen == -1
 * then conversion was not possible;
 */

int
mask2plen (u_int32_t mask)
{
        u_int32_t bitmasks[33] = {
                0x00000000,
                0x80000000, 0xc0000000, 0xe0000000, 0xf0000000,
                0xf8000000, 0xfc000000, 0xfe000000, 0xff000000,
                0xff800000, 0xffc00000, 0xffe00000, 0xfff00000,
                0xfff80000, 0xfffc0000, 0xfffe0000, 0xffff0000,
                0xffff8000, 0xffffc000, 0xffffe000, 0xfffff000,
                0xfffff800, 0xfffffc00, 0xfffffe00, 0xffffff00,
                0xffffff80, 0xffffffc0, 0xffffffe0, 0xfffffff0,
                0xfffffff8, 0xfffffffc, 0xfffffffe, 0xffffffff
        };
        int prefix_len = 33;

        /* lets see if we can transform the mask into a prefixlen */
        while (prefix_len >= 0) {
            if (bitmasks[prefix_len] == mask)
                break;
            prefix_len--;
        }
        return (prefix_len);
}



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